Spectroscopic and theoretical studies of the OCO⋯HF complex in pressurized gases

The spectra of HF-CO mixtures have been measured at T = 300 K in the region of v(HF) and v(HF) vibrations of the OCO⋯HF complex at CO densities increasing from the gaseous to the liquid phase. The evolution of the v(HF) and v(HF) band profiles with increasing system density has been studied. The spectral moments of the two bands and their relative intensities were determined. The spectroscopic data obtained suggest coupling between the large-amplitude librational motions of HF and CO subunits. Excitation of the v(HF) mode may allow the hindered rotational motion of an HF molecule. The spectroscopic result is supported by theoretical analysis. Ab initio calculations at the electron correlation level give a very flat potential-energy surface. The calculated value of the barrier height of the minimum-energy pathway for the complex rearrangement from the linear to the T-shaped structure is 405 cm.